There are many reasons why a guy doesn't ask a girl out, but they fall into a five general categories:
-"I Don't Find Her Attractive"
-"I'm Dating Someone Else"
-"My Friend/Family Would Be Upset"
-"It Will Be Complicated Due To Schedule/Distance"
-"She Won't Say Yes"
Of these six possible reasons, only one has to do with your overall attractiveness or desirability. So you shouldn't immediately assume that the men you like are giving you the cold shoulder because they don't think you're pretty, smart and interesting. It is just as likely that they're dating someone else (or thinking about someone else), or they don't want to upset a friend, or they have a busy schedule, or they think you're indimidating, or they think you're a little crazy.
Regarding that last bit, I'm certainly not saying your crazy. But these men might think you're a bit odd, or 'just one of the guys" or something like that. Please don't develop a complex over it. It's just an option so I brought it up.
In any case, whatever their reason, none of them decided they wanted to ask you out. That doesn't make them bad people and it certainly doesn't make you a bad person. Circumstances and perceptions shape those decisions, and it just seems that in your case with these guys, it didn't work out. Shoud either those circumstances or perceptions change, the situation will change. But if not, you might need to date outside this circle of friends.